Eryngium

(Common Name: Sea Holly).

The common name should refer to one species in
particular: Eryngium maritimum, which grows on beach edges, but it is
now applied to the family as a whole.

Eryngium are varied genus that have in common
thimble-shaped flower heads that are held on branched stems. All attract
bees, butterflies and hover flies. They grow in a wide range of soils
from very free-draining sand through to damp soils. Heights and
flowering times vary.

Most can be propagated from seed, but named
varieties won't come true. Otherwise divide in autumn (not always
successful!) or plant root cuttings in winter.